Spray apparatus

ABSTRACT

Spray apparatus comprising a spray carrier or liquid reservoir ( 1 ), a loop circuit, a first pump ( 2 ) for feeding sp iquid from the liquid reservoir ( 1 ) to the loop circuit (A, B, C, D), a spray chemical reservoir ( 5 ), chemical injection means injecting spray chemical from the spray chemical reservoir ( 5 ) into the loop circuit (A, B, C, D), a spray nozzle ( 6 ), a valve selectively connecting the spray nozzle ( 6 ) to the loop circuit (A, B, C, D), and a second pump ( 4 ) in the loop circuit (A, B, C for continuously circulating spray liquid and spray chemical in the loop circuit (A, B, C, D).

DESCRIPTION TECHNICAL FIELD

[0001] The invention relates to spray apparatus and more particularly toinjected liquid chemical spray apparatus for use in agriculture orhorticulture.

BACKGROUND ART

[0002] As an aid to precision farming it is known to provide chemicalspray apparatus arranged to vary the rate at which a desired chemical isapplied (for example according to local conditions or the ground speedof the spray apparatus) by injecting the chemical directly into thespray carrier or liquid e.g. water shortly before it is applied. In thisthe volume of spray carrier or liquid sprayed remains substantiallyconstant in terms of volume per unit area and only the concentration ofthe sprayed chemical in the spray carried or liquid is varied.

[0003] It is known that chemical injection systems may operate with highor low pressure injection pumps. A high pressure injection pump caninject chemical close to the spray nozzle as it has sufficiently highpressure to overcome the pressure of the pumped water. Unfortunately,however, this makes calibration of the injection system difficult as anychange in the back pressure of the system affects the output of theinjection pump. Low pressure injection injects chemical before thesprayer's main pump where the pressure remains virtually atmospheric.This allows accurate calibration of the amount of chemical mixed withthe water but is slower acting than the high pressure injection sincethe chemical is injected a significant distance from the spray nozzle.

[0004] International patent application WO99/39834 provides sprayapparatus of the kind in which chemical to be sprayed is injected intospray carrier or liquid before the mixture of liquid and chemical issprayed, comprising a closed loop circulating system having a pump withan inlet and an outlet, a loop line connecting the pump inlet andoutlet, a spray nozzle connected to the loop line downstream of the pumpvia a spray line, a spray liquid inlet connected to the loop lineupstream of the pump and a chemical injection system connected to theloop line upstream of the pump, a venturi device having an inlet and anoutlet in the loop line, and having a suction or side port, a returnline connection to the spray line at a position adjacent to the spraynozzle and connection to the suction port of the venturi device, anagitation line connected between the loop line downstream of the venturidevice and the spray line adjacent the spray nozzle and valve means inthe spray line directing liquid flow to the spray nozzle to causereverse flow through the agitation line past the spray nozzle andthrough the return line An object of the present invention is to providean arrangement which provides the advantages of pressure injection ofthe chemical whilst providing fast response between a decision to applya chemical or change its application rate and the required change at thespray nozzle.

DISCLOSURE OF INVENTION

[0005] According to the invention, there is provided spray apparatuscomprising a spray carrier or liquid reservoir, a loop circuit, a firstpump for feeding spray liquid from the liquid reservoir to the loopcircuit, a spray chemical reservoir, chemical injection means forinjecting spray chemical from the spray chemical reservoir into the loopcircuit, a spray nozzle, a valve selectively connecting the spray nozzleto the loop circuit, and a second pump in the loop circuit forcontinuously circulating spray liquid and spray chemical in the loopcircuit.

[0006] Preferably at least one one-way valve is provided in the loopcircuit to ensure liquid flow in one direction only.

[0007] The second pump may be positioned in the loop circuit to receivespray liquid directly from the first pump.

[0008] The valve selectively connecting the spray nozzle to the loopcircuit may be integral with the spray nozzle assembly or alternativelyother valve means may be employed, e.g. a conventional boom controlvalve. In this case the loop circuit may be divided into first andsecond loops controlled by a boom control valve in one of the loopswhich also includes the spray nozzle. A part of the two loops includingthe pump and the chemical injection means, may be common.

[0009] From another aspect the invention is an agricultural orhorticultural spray vehicle comprising spray apparatus as describedabove.

BRIEF DESCRIPTION OF DRAWINGS

[0010] The invention is diagrammatically illustrated by way of examplein the accompanying drawings in which:

[0011]FIG. 1 is a circuit or flow diagram of an agricultural orhorticultural spray apparatus;

[0012]FIG. 2 is a circuit or flow diagram of a modified arrangement ofspray apparatus, and

[0013]FIG. 3 is a circuit diagram generally similar to that of FIG. 1 ofa further modified arrangement of spray apparatus.

BEST MODES FOR CARRYING OUT THE INVENTION

[0014] In the drawings there is shown agricultural spray apparatusgenerally of the kind described in my patent application WO99/39834,which is intended for use where the chemical to be applied is maintainedin concentrated form until immediately before it is to be applied and isonly injected into water or other spray liquid or carrier at the lastmoment before spraying so that there is no requirement for batch mixingof the spray chemical and spray liquid and thus minimum wasting ofchemical and reduced risk of pollution.

[0015] In the present invention in FIG. 1 the spray apparatus comprisesa pair of spray liquid flow loops A and B respectively, the loop A beinggenerally conventional and comprising a tank 1 for spray liquid, usuallywater, a pressure regulator 30, a shut-off valve 32, a conventionalchemical filling hopper 33 and a pump 2 for drawing spray liquid fromthe tank 1 and for returning it to the tank as and when required.

[0016] The loop B is connected to the loop A via a one-way valve 34 toreceive spray liquid therefrom at a flow sensor 3 which feeds a secondpump 4 provided in the loop B to maintain continuous liquid circulationin the loop B. The loop B comprises a parallel series of spray lines 7connected to spray nozzles 6, the spray nozzles being of the kind havingintegral flow control valves, and a chemical injection system 5. Pump 4is a three-port pump having an inlet 35, an outlet 36 and a third port37 at which a depression is created to assist chemical injection intothe third port when the spray liquid or carrier is being forced throughthe pump from the inlet to the outlet.

[0017] Thus in operation during spraying, spray liquid is supplied tothe loop B from the loop A via the pump 2 to replenish liquid sprayedfrom the spray nozzles 6 and chemical is injected into the loop B asrequired. When spraying ceases, liquid circulation in the loop B ismaintained to prevent precipitation or settling of solids in the spraychemical, by the pump 4.

[0018] In FIG. 2 there is shown spray apparatus where the loop B of FIG.1 is replaced by a loop C which is intended to be fed with spray liquidfrom a circuit such as is exemplified by loop A in FIG. 1. Loop C isgenerally similar to that of loop B but in this case a generallyconventional pump 8 having only an inlet and an outlet maintainscontinuous flow in the loop C as described above for loop B and one wayvalves 9 and 10 maintain the desired direction of flow in the loop C andprevent backflow into the loop A. Flow and pressure in the loop C isadjusted by a bypass 11 which short-circuits the pump 8 in the loop Cand which is controlled by a pressure flow control valve 12. A vacuumcontrol valve 13 is positioned in the loop C immediately upstream of thechemical injection system 5.

[0019]FIG. 3 shows a circuit or flow diagram of agricultural orhorticultural spray apparatus generally similar to that of FIGS. 1 and 2but in which the flow control valves integral with the spray nozzles 6are replaced by generally conventional boom control valves 20. It willbe noted that the flow loop D equivalent to the loop B of FIG. 1 or loopC of FIG. 2 comprises two loop parts 23,24 with a common part 25including the circulating pump 8 and three chemical injection pumps 5.The boom control valves 20 are situated immediately upstream of thespray nozzles 6 in loop part 24, and the other loop part 23 forms aby-pass when the spraying is stopped by operation of the boom controlvalves 20, in which case spray liquid is diverted by a three way valve22 at one end of the common part 25 so that circulation continues inloop part 23 when spraying is not occurring.

[0020] It will be noted that the embodiment of FIG. 3 includes agenerally conventional spray liquid mixing chamber 21 in the loop part24.

INDUSTRIAL APPLICABILITY

[0021] The invention thus provides both the benefits of chemicalinjection and of continuous agitation in the spray lines in anagricultural or horticultural sprayer.

[0022] An important advantage of this system is the speed at which thedilution of the product at the nozzle can be changed. This can happeneven when the sprayer is spraying. When the system switches on a pumpduring spraying, the new dilution arrives at all spray nozzles muchquicker than with a conventional system. Conventionally the product canonly be replaced as it is sprayed from the nozzles. This means the lastnozzle on the line of a conventional sprayer is slow to respond to anychange.

1. Spray apparatus comprising a spray carrier or liquid reservoir, aloop circuit, a first pump for feeding spray liquid from the liquidreservoir to the loop circuit, a spray chemical reservoir, chemicalinjection means for injecting spray chemical from the spray chemicalreservoir into the loop circuit, a spray nozzle, a valve selectivelyconnecting the spray nozzle to the loop circuit, and a second pump inthe loop circuit for continuously circulating spray liquid and spraychemical in the loop circuit.
 2. Spray apparatus according to claim 1,comprising at least one one-way valve in the loop circuit to ensureliquid flow in one direction only.
 3. Spray apparatus according to claim1 or claim 2, wherein the second pump is positioned in the loop circuitto receive spray liquid directly from the first pump.
 4. Spray apparatusaccording to any one of claims 1 to 3, wherein the valve selectivelyconnecting the spray nozzle to the loop circuit isl1 integral with thespray nozzle assembly.
 5. Spray apparatus according to any one of claims1 to 3, comprising a generally conventional boom control valve, andwherein the loop circuit is divided into first and second loopscontrolled by the boom control valve in one of the loops which alsoincludes the spray nozzle.
 6. Spray apparatus according to claim 5,wherein a part of the two loops including the pump and the chemicalinjection means is common.
 7. An agricultural or horticultural sprayvehicle comprising spray apparatus as claimed in any preceding claim.